There is a large variety of materials that require a low moisture content for usage, such as clothing. Clothing can be reused indefinitely if properly washed and dried. For this reason, this application will illustrate its usage as a clothes dryer, however, it will be obvious to one of ordinary skill in the art that the instant invention can be used for drying any type of material. The scope of the invention is defined by the claims appended hereto.
A clothes dryer is a modern material dryer used in conjunction with a washing machine which allows a consumer to quickly launder clothing. The conventional clothes dryer employs a rotating chamber which receives damp clothing directly after the wash cycle. Air is drawn into the rotating chamber at atmospheric pressure past a heating element. The heated air is used for drawing moisture from the clothes and the moisture laden air is continually exhausted from the clothes dryer.
The conventional material dryer expends a large amount of energy as the air drawn into the dryer must be heated. The amount of air drawn into the chamber and amount of energy expended during the process is further dependant upon the condition of the air being drawn into the dryer and amount of clothes to be dried. This process is not efficient due to the amount of thermal energy required to heat the air for a drying cycle which may take upwards of an hour to complete. In addition, if a clothes dryer is placed inside a home, the process may cause additional energy loss as the air is drawn from inside the home and expelled outside.
Should the air being drawn have been previously cooled, such as in an air-conditioned home, the cooled air must be heated for the dryer while new air drawn into the home must be cooled. If the home was heated, the conventional dryer again draws treated air requiring the home to replace the air. In this example the heater of the home must operate to replace the air expelled by the dryer.
Should a clothes dryer be placed outside the home, typical of many southern homes, operation of the clothes dryer is affected by the amount of moisture in the air. A high amount of moisture will require the clothes dryer to operate for a longer period of time in order to complete a drying cycle. In addition, most clothes dryers operate on a timing cycle making it impossible to predict an accurate time to discontinue the heating process due to the various conditions of air make-up. Depending upon the weight of the clothes and moisture content therein as well as the type of air being drawn into the clothes dryer, the drying cycle may take upwards of an hour to complete.
It is generally known that the evaporation temperature of a liquid decreases as the pressure of the surrounding air decreases. Thus, water can be drawn from a material at lower temperatures in a near vacuum environment thereby expending less energy if a lower temperature can be utilized. As a result, a number of prior art devices are directed to the modification of clothes dryers which have been developed to incorporate a vacuum or vacuum like chamber. However, these devices lose efficiency in that they constantly pump air into a chamber for purposes of discharging a volume of air and water vapor out of the device by use of a vacuum pump. Such devices require additional power as the incoming air must be circulated and in most cases heated.
For instance, U.S. Pat. No. 3,425,136 discloses a clothes dryer having an interior drum heater and vertical air ducts wherein the device continuously draws air and water vapor from inside a chamber by use of a vacuum pump. Similarly, U.S. Pat. No. 4,041,614 discloses a device which passes air and water vapor through an exit duct to the exterior of a cabinet. U.S. Pat. No. 4,257,173 discloses a "no heat" clothes dryer which simply incorporates a vacuum source coupled to an exhaust port.
U.S. Pat. No. 4,305,211 discloses a clothes drying chamber whereby air and moisture particles from within the chamber are discharged by creation of a suction on the chamber. U.S. Pat. No. 4,615,125 discloses yet another vacuum chamber with a perforated rotatable drum and vacuum pump which draws air and water vapor from the vacuum chamber and contained drum.
U.S. Pat. No. 5,131,169 discloses a clothes dryer with a drum enclosed in a shell having a compressor to remove air and water vapor from the shell. A cyclic operation of pumping heated air into the shell and removing saturated air is employed. U.S. Pat. No. 5,430,956 discloses a clothes drying device employing a turbo engine for drawing air from a drying room and condensing the liquid thereby reducing the volume of air produced by the drying process. U.S. Pat. No. 5,459,945 discloses a vacuum assisted system for drying clothes which includes an evaporation chamber which is located inside a condensation chamber. In this manner the device extracts water from the evaporation chamber by use of a condensation chamber to condense extracted vapor on the outer surface of the evaporation chamber. While the condenser is used, air is continually circulating out of the vacuum chamber by use of the vacuum pump.
Thus what is lacking in the art is a material drying device that eliminates the constant draw of air into the device, lowers the drying temperature, eliminates a constant evacuation by a vacuum pump, and decreases the amount of time to perform a drying cycle thereby reducing energy and operating costs.